panel

1a square or rectangular piece of wood, glass, or metal that forms part of a larger surface such as a door or wallOne of the glass panels in the front door was cracked.see alsosolar panel

2a piece of metal that forms part of the outer frame of a vehicle

3a piece of cloth that forms part of a piece of clothingThe pants have double thickness knee panels for extra protection.

4a group of specialists who give their advice or opinion about something; a group of people who discuss topics of interest on television or radioan advisory panela panel of expertsWe have two politicians on tonight's panel.a panel discussion